This invention generally relates to communication systems and, more particularly, to a wireless communication system.
Generally, participants in a conference may ask questions and make contributions. In large conferences, it requires a microphone system with many microphones and loudspeakers for participants to use or share so that each participant attending the conference may hear the asked questions or contributions from other participants. For example, for meetings or conferences with hundreds or sometime thousands of attendees, it may not be cost effective to set up a system with hundreds or thousands of microphones and associated hardware and management systems. Additionally, sharing microphones among a group of attendees in certain applications or circumstances may cause inconvenience and/or poor audio quality.
U.S. Pat. No. 6,987,992 relates to a wireless microphone system illustrated in FIG. 1. Referring to FIG. 1, the system includes a number of wireless microphones at several remote stations and one signal processing unit at the central station. Each microphone includes an antenna for transmitting speech to a corresponding receiver in the signal processing unit. Thus, the number of receivers in the signal processing unit must be the same as the number of microphones used. As a result, when more microphones are desired, this system would require a large number of receivers at the central station, thereby increasing the size of the signal processing unit and the cost for the system. In addition, the system uses unassigned frequency band for signal transmission between the microphones and the signal processing unit. Because the frequency band is unassigned, it may get interference from other wireless communication devices, thereby increasing signal noise and modulation distortion.
Published patent application WO 99/03253 relates to a method and system illustrated in FIG. 2. Referring to FIG. 2, the system allows conference participants to use a mobile telephone or any other telephone as a conference microphone via Public Services Telephone Network (PSTN) and Public Land Mobile Network (PLMN). The telephone network may via private automatic branch exchange (PABX) connect to a control device which may couple to a loudspeaker device. The system of FIG. 2 uses GSM/VGCS half duplex transmission mode for signal transmission, and thus the signals may not be transmitted and received at the same time. In addition, the system of FIG. 2 may require each conference room to have a set of PABX and control device.
U.S. Patent Publication No. 2006/0187859 relates to a communication system with a number of user endpoints and a conference system, as illustrated in FIG. 3. The user endpoints of FIG. 3 may be an Internet Protocol (IP) phone 32, a computer 33, a cellular phone 34 or a corded telephone 35. The communication networks 40 may include wide area networks (WANs), PSTN, local area networks (LANs), intranets and Internet.